Patent GB-636881-A (GB)
Title: Improvements in or relating to vibration dampers and method of damping the torsional vibrations or oscillations of a rotary mass
IPC: F16F15/173
Filed: 1946-08-15
Abstract: 636,881. Torsional vibration - dampers. HOUDAILLE-HERSHEY CORPORATION. Aug. 15, 1946, No. 24287. Convention date, Sept. 24, 1945. [Class 108 (iii)] A torsional vibrationdamper includes a housing providing a fluid-tight chamber having opposed parallel working surfaces with respect to an inertia mass relatively movable therein, a viscous damping liquid within the housing, the spacing of the. surfaces being such that the fluid film between them resists, with shearing action, relative parallel movement of the surfaces, and is thicker than a mere lubricating film but is of less thickness than a layer of fluid which would afford only a fluid-drag relationship. In the construction shown in Fig. 5, a housing 71 secured to a crank-shaft 73 by three bolts 98 and alternately spaced dowel pins 99, has a hub portion on which fly-wheel discs 74, 75 are rotatably mounted on separated ball-bearing races 93, 93<SP>1</SP>. Axial clearance between the side faces of the discs 74, 75 and the housing 71 and a housing cover-plate 83 is adjusted by separation of the disc under rotation of bolts 77, each of which is in screw-engagement with the disc 75 and is rotatably retained in the disc 74 by a spring ring 79. In a modified construction (Fig. 7, not shown) the ball-bearings are replaced by plain bearings. In a further construction (Figs. 3, 4, not shown) axiallyspaced annular discs are mounted on either side of a single fly-wheel and are secured at their inner periphery by circumferentiallyspaced rivets and spacing rings to the fly-wheel boss. A second series of axially-spaced discs arranged in interleaving relation with the side surfaces of the fly-wheel and with the fly-wheel discs are secured around their outer periphery by rivets and spacing rings to a cylindrical housing rigidly connected with the crank-shaft. The housing is filled with oil by means of filler and vent holes which are then closed by solder plugs. In a further construction (Figs. 8, 9, not shown), a housing keyed to the crank-shaft has a hollow annular space in the outer peripheral portion of which is disposed an annular fly-wheel connected with a boss rigid with the crank-shaft by a coiled torsion spring. In the construction shown in Fig. 12, in which provision is made for the damping of two separate modes of vibration, an annular fly-wheel 151 is bolted to a disc 153 which is resiliently connected to a base 157 by an integral torsion stem 155. A second torsion stem 156 integral with the disc 153 is also integral with a disc 154 bolted to a second annular fly-wheel 152 spaced from the fly-wheel 151 by a clearance 162. The base 157 is bolted and dowelled to the crank-shaft 159 and is welded to a fluidcontaining housing 134 which is in threaded engagement with a cover 139. Axial adjustment of the cover 139 to vary the clearance with the outer side face of the disc 154, is effected by relative rotation of the cover 139 and the housing 134. Control of the degree of rotation, and locking of the cover 139 to the housing 134 is effected by the engagement of tabs 143 connected by screws 146 with the cover 139, in radial slots which are spaced at 45 degrees around the outer periphery of the housing. In operation, the fly-wheels 151, 152 oscillate in unison about the torsion stems 155, 156 for the vibrations of one mode and oscillate in opposite directions for vibrations of the second mode. In a modification of this construction suitable for damping one mode of vibration only, one fly-wheel 151, only, and associated disc 153 and stem 155 is provided. The viscous fluid is preferably a silicone such as Dow-Corning fluid number 200.